To Install Stucco Right, Include an Air Gap
In many areas of the country, hundreds of stucco-clad homes have suffered wall rot. Although building scientists are still researching the causes of wall rot behind stucco, it’s clear that all of these walls got wet and were unable to dry.
Among the reasons that have been proposed for the recent epidemic of stucco-clad homes with wall rot, there is one thing they all have in common, all the homes lacked a ventilated air gap between the stucco and the sheathing. Full article here